US5025815A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Polyolefin filter tow and method of making it
Assignee: Filter Materials Ltd
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Filing: 1988-08-10
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Granted: 1991-06-25
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Expires: 2008-08-10
Abstract
Abstract A polyolefin material having improved fibrillation properties, allowing one to achieve higher yield in cigarette filters made from the fibrillated material is provided. The material includes between about 70% and about 99% of at least one polypropylene homopolymer with a melt index of between about 1.2 to about 3.0 (measured according to ISO standard 1133 at 230° C., 2.16 kgf) and a density of about 0.905 g/cc, and between about 1% and about 30% of at least one low density polyethylene homopolymer with a melt index of between about 0.9 and 3.0 (measured according to ISO standard 1133 at 190° C., 2.16 kgf) and a density of about 0.921 g/cc.
Inventors
- 👤 Michael Hill
- 👤 Walter A. Nichols
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 06:52
CPC Classifications
D; D01; D01D; D01D5/00; D01D5/42; A; A24; A24D; A24D3/00; A24D3/06; A24D3/16; A24D3/08; D01D5/423
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
136 words
A method of making a polyolefin filter tow, said method comprising, in the listed order, the steps of: forming a polyolefin film having a molecular structure, said polyolefin film comprising between about 70% and about 99% of at least one polypropylene homopolymer, and between about 1% and about 30% of at least one low density polyethylene homopolymer; orienting said molecular structure by heating said film to just below the melting point of said film and stretching said heated film; fibrillating said oriented film to form an interconnected fiber web; crimping said fibrillated web; and forming said crimped fibrillated web into filter tow, said filter tow having a yield of at least about 60%, said yield being defined as a dimensionless ratio of filter pressure drop expressed in millimeters of water to filter weight expressed in milligrams.
Claim 2
Independent Claim
136 words
A method of making a polyolefin filter tow, said method comprising, in the listed order, the steps of: forming a polyolefin film having a molecular structure, said polyolefin film comprising between about 70% and about 99% of at least one polypropylene homopolymer, and between about 1% and about 30% of at least one low density polyethylene homopolymer; orienting said molecular structure by heating said film to just below the melting point of said film and stretching said heated film; fibrillating said oriented film to form an interconnected fiber web; crimping said fibrillated web; and forming said crimped fibrillated web into filter tow, said filter tow having a yield of at least about 60%, said yield being defined as a dimensionless ratio of filter pressure drop expressed in millimeters of water to filter weight expressed in milligrams.
Claim 3
Dependent Claim
44 words
The method of claim 1 wherein said forming step comprises forming a polyolefin film comprising between about 90% and about 99% of said at least one polypropylene homopolymer and between about 1% and about 10% of said at least one low density polyethylene homopolymer.
Claim 4
Dependent Claim
74 words
The method of claim 1 wherein said forming step comprises forming a polyolefin film comprising at least one polypropylene homopolymer having a melt index between about 1.2 and about 3.0 (ISO 1133; 230° C., 2.16 kgf) and a density of about 0.905 g/cc, and at least one low density polyethylene homopolymer having a melt index between about 0.9 and about 3.0 (ISO 1133; 190° C., 2.16 kgf) and a density of about 0.921 g/cc.
Claim 5
Dependent Claim
30 words
The method of claim 3 wherein said forming step comprises forming a polyolefin film comprising at least one polypropylene homopolymer having a melt index between about 1.8 and about 2.5.
Claim 6
Dependent Claim
32 words
The method of claim 3 wherein said forming step comprises forming a polyolefin film comprising at least one low density polyethylene homopolymer having a melt index between about 1.0 and about 2.0.
Claim 7
Dependent Claim
24 words
The method of claim 1 wherein said forming step comprises forming a polyolefin film comprising between about 0.15% and about 5.0% of an extender.
Claim 8
Dependent Claim
29 words
The method of claim 1 wherein said forming step comprises forming a polyolefin film comprising between about 0.15% and about 5.0% of an extender which is a coloring agent.
Claim 9
Dependent Claim
41 words
The method of claim 7 wherein said forming step comprises forming a polyolefin film comprising between about 0.15% and about 5.0% of a material selected from the group consisting of titanium dioxide, carbon black, clay, calcium carbonate, silica, and mixtures thereof.
Claim 10
Dependent Claim
22 words
The method of claim 8 wherein said material is added to at least one of said polymers before said film is formed.
Claim 11
Dependent Claim
16 words
The method of claim 8 wherein said material is added in the form of a masterbatch.
Claim 12
Dependent Claim
17 words
The method of claim 8 wherein said material is added as part of a liquid carrier system.
Claim 13
Dependent Claim
14 words
The method of claim 8 wherein said material is blended directly with said homopolymers.
Claim 14
Dependent Claim
64 words
A polyolefin filter tow, comprising between about 70% and about 99% of at least one polypropylene homopolymer and between about 1% and about 30% of at least one low density polyethylene homopolymer, and having a yield of at least about 60%, said yield being defined as a dimensionless ratio of filter pressure drop expressed in millimeters of water to filter weight expressed in milligrams.
Claim 15
Dependent Claim
64 words
A polyolefin filter tow, comprising between about 70% and about 99% of at least one polypropylene homopolymer and between about 1% and about 30% of at least one low density polyethylene homopolymer, and having a yield of at least about 60%, said yield being defined as a dimensionless ratio of filter pressure drop expressed in millimeters of water to filter weight expressed in milligrams.
Claim 16
Dependent Claim
36 words
The filter tow of claim 13 comprising between about 90% and about 99% of said at least one polypropylene homopolymer and between about 1% and about 10% of said at least one low density polyethylene homopolymer.
Claim 17
Dependent Claim
69 words
The polyolefin filter tow of claim 13 wherein said at least one polypropylene homopolymer has a melt index between about 1.2 and about 3.0 (ISO 1133; 230° C., 2.16 kgf) and a density of about 0.905 g/cc, and said at least one low density polyethylene homopolymer has a melt index between about 0.9 and about 3.0 (ISO 1133; 190° C., 2.16 kgf) and a density of about 0.921 g/cc.
Claim 18
Dependent Claim
24 words
The polyolefin filter tow of claim 15 wherein said at least one polypropylene homopolymer has a melt index between about 1.8 and about 2.5.
Claim 19
Dependent Claim
26 words
The polyolefin filter tow of claim 15 wherein said at least one low density polyethylene homopolymer has a melt index between about 1.0 and about 2.0.
Claim 20
Dependent Claim
18 words
The polyolefin filter tow of claim 13 further comprising between about 0.15% and about 5.0% of an extender.
Claim 21
Dependent Claim
14 words
The polyolefin filter tow of claim 18 wherein said extender is a coloring agent.
Claim 22
Dependent Claim
28 words
The polyolefin filter tow of claim 19 wherein said extender is selected from the group consisting of titanium dioxide, carbon black, clay, calcium carbonate, silica, and mixtures thereof.
Claim 23
Dependent Claim
38 words
The method of claim 1 wherein said step of forming said crimped fibrillated web into said filter tow comprises forming said crimped fibrillated web into a filter tow having a minimum yield between about 60% and about 80%.
Claim 24
Dependent Claim
38 words
The method of claim 1 wherein said step of forming said crimped fibrillated web into said filter tow comprises forming said crimped fibrillated web into a filter tow having a maximum yield between about 65% and about 92%.
Claim 25
Dependent Claim
20 words
The polyolefin filter tow of claim 13, said filter tow having a minimum yield between about 60% and about 80%.
Claim 26
Dependent Claim
20 words
The polyolefin filter tow of claim 13, said filter tow having a maximum yield between about 65% and about 92%.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-06-24 | 1994-12-24 | 1995-06-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-06-24 | 1998-12-24 | 1999-06-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-06-24 | 2002-12-24 | 2003-06-25 | $7700.00 | Window Closed / Lapsed |